Over the last two decades, the electronics industry has witnessed rapid development and expansion of new devices and entire technologies evolving from the devices themselves. For example, efforts to reduce cost, size, power consumption, and improve on speed, bandwidth, isolation, etc., of components and systems have resulted in the development of integrated circuits and their evolution into LSI, VLSI, and IOC (integrated optic circuits), the latter employing optical dielectric waveguides.
Within this sector of component development, a number of optically responsive devices, such as light controlled switching devices (e.g. thyristors, optically responsive FETs, etc.) have been proposed. One such switch device which is purported to have particular utility in switching signals at microwave frequencies is described in the U.S. patent to Auston, U.S. Pat. No. 3,917,943.
In accordance with the proposed device, a microstrip configuration having a gap in a conductive strip that forms the signal carrying path is selectively illuminated by a first beam of light for temporarily providing a high electrical conductivity region in the surface of the semiconductor bulk material between separated ends of the conductive strip, whereby the device is effectively turned-on, providing a signal carrying path through the conductive strip and the illuminated surface of the semiconductor bulk at the gap in the strip. To turn the device off, a second beam of light, to which the bulk responds, must be directed at the device, creating an effective short circuit from the conductive strip, through the bulk itself, to a ground plane disposed on the bulk material.
Unfortunately, because of its configuration and mode of operation, this device requires considerable driving power (on the order of several watts) to trigger the switch, is subject to cross talk problems and has limited bandwidth (as separate switching control signals are required for turning the switch on and off).